Problem: In his chemistry class, William took 5 exams. His scores were 75, 89, 76, 85, and 75. What was his average score on the exams?
The average is the sum of his scores divided by the number of scores. There are 5 scores and their sum is $75 + 89 + 76 + 85 + 75 = 400$ His average score is $400 \div 5 = 80$.